Facing Fear

July 6th, 2011 The Connectome

New neuroscientific studies are shedding light on the allure of dark forests and eerie old houses…and cliff diving.

Sensational!

In psychology, this drive to explore the unusual is one manifestation of the behavior pattern known as “sensation-seeking” – the tendency to pursue intense, novel experiences out of curiosity, or just for the sheer joy of excitement.

Though the behavior of sensation-seekers has been thoroughlystudied, the exact reasons for that behavior – and the neuroscience behind those reasons – are only now beginning to be unraveled. As a report in the journal Psychological Science explains, the brains of people who seek out thrills and mysteries actually behave differently from those of more cautious people.

Now, for me, this is about is about as awesome as life gets – my two great loves are weird mysteries and neuroscience, and I’ve spent most of my adult life exploring the the enigma of why the human mind is so fascinated by enigmas. But anyway, on to the data!

A group of researchers led by Dr. Jane Joseph at the University of Kentucky used fMRI to study subjects’ neurophysiological responses to various types of “strongly arousing” stimuli. They discovered that these stimuli activate different cerebral regions, depending on whether or not the subject was a sensation-seeker:

Regardless of whether the pictures were pleasant (e.g., mild erotica) or unpleasant (e.g., a snake poised to strike), the high-sensation seekers showed early and strong activation in the insula [a cerebral area involved in what might be called “raw” emotions and sensations, such as excitement, pride, hunger, and lust]. In contrast, in the low-sensation seekers, insula activity barely rose above baseline levels.

The brains of these more conservative subjects responded with increased activity in the anterior cingulate cortex (ACC), an area involved in anticipation of errors and conflicts. What’s interesting is that ACCs of sensation-seekers eventually reached similar levels of activation, but took much longer to get there. It’s possible that their brains were responding first with sheer excitement, and only later considering the possibility of danger or failure:

“If you look at the data, you can see that the insula response in the lows starts to rise, just as in the highs, but then the anterior cingulate kicks in and almost seems to deflect the insula response in the low-sensation seekers,” Joseph said.

Sensation-seeking behavior can sometimes be linked with the personality trait known as novelty-seeking, which plays out as an impulsive tendency to explore new stimuli, even to the point of irresponsibility or personal harm. While a moderate amount of novelty-seeking can be evolutionarily beneficial – we might call it “bravery” in such cases – an excess is obviously dangerous.

Some studiessuggest that novelty-seeking may be linked to a deficiency in midbrain D2 receptors, which process the “reward” and “motivation” chemical dopamine. Studies on another type of dopamine receptor seem to show an almost opposite effect: sensation-seeking may be linked with higher numbers of D4 dopamine receptors.

The exact mechanisms at work here are still uncertain: it may be that when it’s harder for someone to feel the joy of a thrill, they’ll go further than normal to get it; it’s also been suggested that D2 receptors act as “brakes” on dopamine release, so a deficiency of them would actually allow more dopamine to pump around.

Still, many of us who don’t qualify as real-life novelty-seekers still love to watch thrilling or scary movies now and then. In those cases, the ACC may actually be helping us enjoy the show:

Thrill-seekers may be able to use cognitive parts of the brains to recognize that the scary movie or ride isn’t really going to hurt them … They can put the brakes on the flight and avoidance response and experience the emotional salience of the fear.

The difference between cliff divers and horror fans, it seems, may be less a matter of taste, and more a matter of response threshold. In other words, the safer we feel, the more fun it is to be scared.

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The human brain contains around 84 billion neurons, making several hundred trillion interconnections. The better we understand these patterns of connectivity, the better we understand ourselves. In short, neuroscience is awesome. This is a blog about it.